The present invention relates generally to the field of automated conveyor systems, and, more particularly, to conveyor systems used for changing the direction and orientation of transported product.
For mass production of printed media, conveyor systems are used to transport product between workstations where a variety of operations are performed as part of the production process. It is often necessary, however, to position the product on the conveyor system in a particular orientation to facilitate the execution of a particular operation. Consider paper products, for example. Product is conveyed out of the folding unit of a printing press with the fold on the side. That is, the fold is parallel with the transport direction. When the product is delivered to a stacking machine or for one of the operations of an in-line trimming machine, however, the folded edge must be leading (i.e., perpendicular to the transport direction). To perform this reorientation, drop turn systems are used in which a conveyor is positioned at a right angle to the transport conveyor carrying the product stream to reorient the product stream through redirection.
Existing conveyor systems used in reorienting product through product flow redirection suffer from the disadvantage that product often becomes misaligned or unevenly distributed during the 90.degree. transfer. Product distribution can be critical depending on the application. For example, stacking machines include a counting device to ensure the stack is quantisized properly. If product units overlay one another, the count generated will be incorrect resulting in an inaccurate stack to be delivered to a customer. If too much product is contained in a stack, excess printing cost is incurred. If too little product is in a stack, all customers may not be served. If product is severely misaligned, the stacking machine could jam resulting in increased maintenance costs. Similar jams can occur in in-line trimmers.
Generally, alignment problems are most acute when the drop turn system is running very slow. Under slow speed, product tends to roll or misalign during the transfer from one conveyor to a perpendicular conveyor. Existing drop turn systems have been ineffective at reorienting product streams running at slow speed without incurring frequent alignment problems. Additionally, when running at very high speeds, a traditional drop turn system can also fail.
Accordingly, there exists a need for a conveyor system capable of changing product orientation through redirection of product flow at right angles that overcomes the aforementioned disadvantages of prior art systems.